As will be apparent from the literature identified above, the packaging of radioactive wastes is a well developed field in which care must be taken to minimize environmental contamination with the radioactive materials which are to be packaged for transport or storage. It is important in many cases to minimize the volume of material which must be handled and it has, therefore, been proposed to dry the radioactive wastes, e.g. by the evaporation of water therefrom.
The containers in which the wastes can be packaged can be, for example, massive iron structures in which the comparatively thick walls of the container constitute a shield against penetration by the radio nucleated decay particles or rays or can be equipped with cells or channels containing shielding materials with, for example, a enhanced neutron cross section.
The containers may be provided with binders in which the radioactive materials are captured to prevent them from leaching out of the containers should there be some damage to the containers with time. The containers are generally sealed to prevent the escape of any radioactive material.
The packaging of radioactive wastes in this manner can be utilized for the short-duration or temporary storage of the wastes, e.g. prior to reprocessing, or for the transportation of such wastes, e.g. from a nuclear power plant to a spent-fuel processing station or from a spent-fuel processing plant to a waste disposal site, or from a nuclear power facility directly to the waste disposal site.
Most commonly, however, the containers serve for the ultimate disposal of the radioactive wastes, i.e. to hold the wastes substantially permanently at the waste disposal site.
It is known to introduce such wastes, if desired together with a hardening or binding agent, into the containers, by first evacuating the containers, and then allowing the subatmospheric pressure which is thereby developed in the container to draw the radioactive waste into the container. Since the container may be maintained under suction during this process, gaseous and even gas-entrained substances are sometimes drawn off and passed through a filter or the like before being released into the atmosphere or subjected to some other treatment.
Up to now, to the extent that the radioactive waste has been moist or wet, the moisture is retained in the packaged product which has created a corrosion problem with time. The corrosion problem is especially pronounced because the normal decay of the radioactive material tends to raise the temperature within the waste-packaging container, the elevated temperature accelerating chemical corrosion or attack upon the walls of the container.
This has been recognized heretofore and hence it has been proposed to dry the product before introducing it into the container, in which case transfer into the container by vacuum as described is not possible or convenient.